60 PROCEEDINGS OP THE AMERICAN ACADEMY 



I. 0.5214 grm. of the substance dried over HjSO^ gave on ignition 

 with HjSO^ 0.5296 grm. PbSO^. 

 II. 0.2900 grm. of the substance gave 0.2960 grm. PbSO^. 



Calculated for PbCCHOjjj. Found. 



I. IT. 



Pb 69.69 69.42 69.71 



The presence of formic acid, and the quantity of the distillate which 

 collected between 40° - 50°, suggested the possible formation of me- 

 thylal. This fraction was therefore treated with an equal volume of 

 water, and the oil which separated boiled with plumbic hydrate to 

 decompose the methyl formiate. After drying with fused calcic 

 chloride, the residue distilled above 50°. In another attempt to iso- 

 late methylal, 2,000 grms. of (a) were fractioned, and the distillate 

 below 50° examined according to Dancer's method* for the sepa- 

 ration of dimethylacetal. As in the first experiment, the residue 

 distilled at a temperature far above the boiling point of methylal, 

 which seemed to indicate that this substance could not have been 

 formed in any appreciable quantity. 



Methyl Acetate. 



Since the fractions 50° -52° and 52° -54° gave reactions for alde- 

 hyde and acetone, they were evidently a mixture of these substances 

 with methyl acetate. The greater part of the methyl acetate in (a) 

 and {])) was collected in the fraction 54° -56°, which boiled constant at 

 54°. 5 -55°. 5 (Bar. 769.5 mm.). To determine approximately the 

 percentage of methyl alcohol in this fraction, 655 grms. were saponi- 

 fied with potassic hydrate, and distilled. After drying with fused 

 potassic carbonate and distilling off the methyl alcohol, there were 

 obtained 255 grms., which came over between 66° and 67° (Bar. 

 769.5 mm.), or 92 per cent, of the amount required from the weight 

 taken of methyl acetate. In repeating this saponification in a dilute 

 solution of methyl acetate, with a potassic hydrate solution of known 

 strength, the excess of alkali was titrated with standard sulphuric acid, 

 and the percentage of methyl acetate calculated from the amount of 

 potassic hydrate required to decompose it. This method gave 99.2 

 per cent of pure methyl acetate. 



* Ann. Chem. Pharm., cxxxii. 240. 



